Integrated circuits require input/output buffers for driving signals to/from other parts of the integrated circuit. There are two basic modes of signaling namely, differential mode and single-ended mode. Single-ended signaling requires a reference voltage; variation around this reference voltage is registered as a high or low signal whereas in differential signaling the signal provides its own reference. Differential signaling provides advantages over single-ended signaling in terms of signal swing, noise immunity etc.; however, the choice of signaling mode depends upon the nature of the application.
To support both types of signaling modes present day integrated circuits provide separate Input/Output (I/O) blocks. However, this approach requires, for instance, additional pins thereby increasing the size and cost of the integrated circuit. It is therefore desirable to enable I/O blocks of integrated circuits to support both modes of signaling.